Low birth weight (LBW) infant (1800-2449 gram) will be given the new human milk fortifier (HMF) which contains protein, lipid, carbohydrate and micronutrients after discharge. Human Milk Fortifier or placebo (carbohydrate only with similar calorie content) will be provided until 3 months of age. The investigators want to evaluate if the addition of HMF to mother's milk while breastfeeding LBW infants after discharge influences growth and body composition up to 3 months of age.

This is a prospective two arms parallel double-blind randomized clinical trial in LBW infants. Clinically healthy LBW infants discharge on oral feeding of human milk before 2 weeks of age (< 15 days old) will be invited to participate in the study. Exclusively or predominantly breastfed infants will be encourage to use finger feeding as method of supplementation, but mothers can choose their own preferences if they wish to do so.

After signing the informed consent by parent, subject will be randomized to one of four group. Randomization list were prepare by one investigator who do not involve in recruitment, outcome measures and statistical analysis. Study product will be labeled as A, B, C D in similar tin. Only manufacturer know the content of these tins and the code will be revealed after statistical analysis completed. Parents will be given this 200 g tin of study product and ask to return the tin after 14 days of opening. Unblinded assistant will weight the tin before and after opening to estimate the HMF intake for 14 days.

This study will be conducted in several hospitals in Greater Jakarta.

Adherence to study protocol will be encouraged during face to face session initially in dispensing study product and subsequent visits (visit 1 at one-month-old, visit 2 at two months old). These sessions will include the reminder of the importance of following study protocol, breastfeeding support if needed and discussion about difficulties that arise. The investigators will also remind mothers via text to fill in three days diary of intake one week before each visit.

Inclusion Criteria:

1. Low birth weight infants (1800-2499 g) with oral feeding
2. Exclusively breastfed or predominantly breastfed (consuming term infant formula less than 50 ml/Kg BW/day) at discharge
3. Discharge from the hospital before 2 weeks of age and maximal age of enrolment is 14 days old
4. Live in greater Jakarta
5. Parents agree in writing to study participation and indicate their intention to follow study procedures.

Exclusion Criteria:

Any subject who has major congenital anomaly or any other disorder(s) that infers with normal feeding, growth, and neurodevelopment.

Participating in another intervention trial

Study protocol will be published in a scientific journal. Others data will be available upon request to principle investigator.

Upon acceptance in scientific journal in one year from data completion

Open access according to the journal

One investigator who do not involve in recruitment and outcome measures will generate randomization list by computer application and set up the list into Redcap randomization set up. No one except him will know the sequence of randomization. Research assistant will randomize subjects into one of four group according to Redcap assignment. The manufacturer prepare the study product into four groups: A,B,C,D and kept the code until the statistical analysis completed. All investigators, care providers and study subjects aware of the active or placebo group. Research assistants who recruit the study subject are not allowed to open the tin. One research assistant who does no meet study subject will measure the weight of tin before and after the supplementation.

Subject only meet with researchers individually and will not meet other subjects so they will not know the content of the other tin.